May 27, 2019 | Mark Paradies

Monday Accident & Lessons Learned: Aliso Canyon Gas Storage Well Leak

Root Cause Analysis Finally Available

• • •

Almost two years ago (July 18, 2017) we wrote an article about how long a root cause analysis should take. The bad example was the investigation of an uncontrolled gas leak of a Southern California Gas Company natural gas storage facility in Aliso Canyon.

On May 16, 2019, the investigation root cause analysis report was finally published by the California Public Utilities Commission. Here is a video that describes the findings:

The original leak was discovered on October 23, 2015, and the leak was finally stopped on February 11, 2016.

If the investigation started on February 11, 2016, the final root cause analysis report by the California Public Utility Commission (and eventually performed by a contractor, Blade Energy Partners) over three years to complete and publish.

You can read the full report HERE or just watch the video to see what their findings were.


One interesting part of the root cause analysis was the headlines that it generated. Here are some examples:

Associated Press: Utility, regulatory failures led to biggest US gas leak

Los Angeles Daily News: ‘Root cause’ report blasts SoCal Gas over massive 2015 Porter Ranch gas leak

Reuters: California utility in big 2015 gas leak had failed to probe leaks for decades

Bloomberg: Climate Changed – Biggest U.S. Gas Leak Followed Years of Problems, State Says

It is interesting how the different news agencies spun the information in the 250+ page report. Was it the regulator’ fault? The company’s fault? It seems the headlines were mainly focussed on blame. That should make us question what we are interested in as readers.

Also, these headlines should make every company consider the bad press and loss of company reputation that occurs whenever an accident like this makes front page news. And this news has continued for years.


Bloomberg reported that the leak has already cost more than $1 Billion. The Los Angeles Daily News reports that there are 390 lawsuits that include 48,500 people still outstanding.

This is another good example of how much money can be saved by good troubleshooting and root cause analysis BEFORE a major accident happens.

Root Causes

The contractor that performed the root cause analysis used a cause and effect based system (fault tree) to analyze the root causes of the leak. This resulted in root causes that included:

  • No regulation on production casing wall thickness
  • No corrosion protection
  • Not proactive in managing failures
  • No evidence of kill modeling
  • Thought they could top kill

This demonstrates the variation in the definition of a “root cause” when using these kinds of techniques. For example, you might want to ask …

  • Is the regulation of casing wall thickness needed?
  • When and why would you decide to use corrosion protection?
  • Is no evidence of modeling a cause or is it the failure to model?

This starts to make you appreciate the guidance provided in TapRooT® that helps you find fixable Specific and Generic Root Causes.

Also, if a TapRooT® User reviews the cause and effect chart on page B-2 of the report, you get an idea of the usefulness of the SnapCharT® Diagram in understanding what happened and presenting the results of your root cause analysis as compared the cause and effect chart.

Adequate Corrective Actions?

Finally, four of the root causes:

  • ID180: No regulations required failure analysis
  • ID108: No failure analysis of any of the prior casing failures
  • ID178: Failure analysis was not considered necessary
  • ID184: Not proactive in managing failures

Had the suggested solution of:

“Regulation should require a Level 1 (per API 585) analysis of any failure” (page 235)

But the report then listed this suggestion as “not applicable” to SoCalGas and “not specifically addressed by regulation” by the California Public Utilities Commission.

These “root causes” had to do with previous incidents of leakage that were not thoroughly investigated by SoCalGas. We frequently talk about the need for thorough root cause analysis of precursor incidents. These previous leaks, although fairly easily controlled, were precursors for the major leak that was the subject of this investigation. The report seems to imply that failure to perform adequate root cause analysis on well leaks has still not been addressed by SoCalGas or the California Public Utilities Commission. If this is true, it is certainly a major oversight.

This oversight should make you think …

“Do we perform adequate root cause analysis
of precursor incidents at our company?”

Finally, who is ultimately responsible for safe, efficient, environmentally sound operations of a facility? Does every action of a company need to be regulated? It seems that is the answer that people seem to gravitate toward after an accident.

What Should You Do?

Have you adequately assessed the risks of your operations?

Do you have systematic, easy to understand guided root cause analysis tools?

Do you use these tools to evaluate precursor incidents and prevent major accidents?

How much is it worth to prevent a major accident at your facility?

We believe that investing in thorough, credible, explainable, root cause analysis is one of the best investments that your company can make. Your decision to implement a policy to investigate precursor incidents is critically important to your company’s success. This accident should help you realize how important that decision is.

Accident, Current Events, Process Safety, Root Cause Analysis, Root Cause Analysis Tips
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